Flotation of cement copper



iatented Feb. 9, 1937 UNITED STATES PATENT OFFICE 5 Claims.

Itiswelltnorwninthe art that oxidized forms of copper may he recovered as high grade cement copper concentrate by leaching the ore with sulphuric acid, precipitating the dissolved copper with metallic iron in presence of the pulp and recovering the precipitated cement copper from the pulp by flotation. It isalso known that the combination of dissolved iron salts such as exist in the above mentioned flotation circuit together with aeration occurring in flotation results in resolution of cement copper to such an extent that means have been adopted for its prevention, such as are described inmy Patent No. 1,971,416, dated Aug. 28, 1934.

I have found that in the flotation of cement copper in which middlings or cleaner rejects are produced, as in standard flotation practice and which require further concentration treatment to produce satisfactory end-products, such middlings or rejects become less amenable to flotation after re-circulation or further treatment in the flotation system, with the result that re-circulatin loads of middlings are built up which eventually discharge largely into the tailings, thus causing excessive copper losses. I have also found that the above copper losses resulting from re-circulating products are caused by both re-solution and oxidation 01' cement copper and that even it resolution is prevented oxidation of solid copper may take placefthus giving non-floatable products carrying copper values.

The invention here specified deals with a method of reconditioning cement copper flotation middlings or rejects before their return to the flotation circuit so that this copper is rendered amenable to recovery in the final flotation concentrate. It is not the intention to limit this method to any speciflc flow sheet or arrangement of the flotation cells as it is applicable to many types of flotation circuits and conditions. For example, in the usual rougher flotation system a single concentrate or a series of concentrates of varying grades may be taken and the grade of any or all of these may or may not be raised by subsequent cleaning operations. Also in cleaner operations rejects may be produced containing copper values. However, I have found that such products become less amenable to flotation by repeated aeration. According to this invention, any middling, reject or intermediate concentrate from any stage in the cement copper flotation may be treated so as to convert unfloatable oxidized or combined copper back to a floatable form and this product then returned to the flotation circuit so that the previously unfloatable copper in the mid- Benewed July 3, 1986 dlingismadeamenabletoflotationandissuhstantially recovered in the form or a flnal concentrate, either as a separate concentrate or as a part of the main concentrate. In contra-distinction to standard flotation practice and the known prior art, this reconditioning is not brought about by simply adding additional or diflerent flotation reagents nor by freeing locked mineral grains be re-grinding, but is accomplished by eii'ecting a change of chemical state oi the copper which was caused to be refractory with respect to flotation as a result of previous aeration. Ibis is preferably accomplished by re-forming, as finely divided cement copper, of metallic copper surtaces by chemical action, but may also be carried out by treatment which converts the refractory or non-floatable copper to a floatable form other than metallic, such as sulphide particles or sulphide-filmed particles.

It is the aim of this specification to disclose the fact that, in contrast to natural mineral substances, cement copper rapidly changes its original characteristics in the course of plant operations which involve aeration and as a result of this fact non-floatable or diflicultly floatabie copper compounds are formed and exist in the intermediate flotation products. In order, thereiore, to produce a high grade concentrate and a low grade tailing in flotation these intermediate products require a special treatment before they ultimately find their way into the end products of the flotation system. The invention here described deals with the means adopted to convert the copper in these products back to a floatable form and also the general method involved in adding the intermediate products to the flnal end products 01' the flotation system.

When inhibiting re-solution by use of a basic precipitant between the stages of copper precipitation byiron and cement copper flotation, as described in my above mentioned patent, any copper remaining in solution, after contacting with iron, is almost completely precipitated as copper hydroxide by the basic precipitant. This copper hydroxide, being difllcultly floatable, is at least partially floated in the rougher flotation treatment, but is dropped in the cleaner and this tends to accumulate in the cleaner rejects and intermediate concentrates and eventually is largely discharged into the tailing. In such cases the present invention flnds an important application as by the treatment 0! intermediate flotation products herein disclosed the copper hydroxide is converted to a more floatable form, suchas cementcopper,andasaresultoisubsequent liotatim is ultimately recovered as a high rade Still another feature of this invention is the recovery of copper initially in solution and not precipitated prior to flotation treatment. Certain portions of such disolved copper are carried over into the concentrate as a part of the pulp solution and are by my method thm converted to floatable copper in coniunctirm with the dissolved copper caused by resolutim in the system, which has been previously described.

or whether or not re-solution existslnthenysianorhss been inhibited by useof a bade l'eci itsnt prior to cement copper flotation, or whether dhsolved copper is initially present in flotaflm, the general means and method here specified may be blindly cmductcd as follows, and is subject to wide variation in manipulation without departingtrmthespiritandpurposecfthisinvenflm.

the oxkllsed copper ore, after being ground lnthefillredi'ashim, sayto2% plus 48 mesh, may he give: a preliminary flotation treatment tor sul ilir'e thickened to the desired degree, In; to 50 per cent solids, leached with sulphuric sold In agitation, treated with metallicirmsuehsssponge ironor fine scrap in asulhfleaniarahisaichasanagitator tankor revolving drum. auditioned for flotation by addition oi suitable Ihtation reagents and perhaps a limited quantity oi basic precipitant to complete the copper lreclpitation and also precipitateaca'talnportionofdissolved ironasierrous hydroxide, and flna'lly treated by flotation i'or recess: 1! copper. In this flotation treatment dcement comer aflnal tailing is produced, together with a flnal cement copper concentrate.

with a flnal concentrate 01' 55-80 per cunt cows. The intermediate flotation products with which this invention is concerned vary in grade anywhere between the value solid oxidlad copper. the latter being either completelyoxidindpartielesorfllmsoi copperoxideon the current mppuparticles. In either case bothtlm dissolved and forms or copper are converted to a floatshle i'orm, preferably flnely divided cunent copper. If conditions in the previous flotstim have been conducive to re-solutim oi cement copper there will be a relatively large amount at dhsolved copper present and theamountoisolidoxidizedcopper mayberelatlvely small (I e. However, it re-solutimhasbemprevented there maybean appreciableammtoi'solidoxidlsedcopper or oioxide flhnsmhlwhiehcasethehydrogenion concentratim of the pulp solution is raised by addingalimiiedquantityotacidandagitating (but not suhstantialb aerating) the reject pulp. This treatment raters the metallic c ppe 8 1 face to the oxide coated particles, dissolves the completely oxidized particles and the copper in solution. The dissolved copper in the pulp is then precipitated as finely divided cement copper by contact with metallic iron, as in an agitator, drum or mill. By limiting the acid so added and avoiding aeration the copper oxide (and hydroxide if present) is dissolved in preference to the cement copper. After the dissolved copper has been precipitated in a floatable form the material, the copper content 01' which is now practically all amenable to flotation, is sent to a suitable place in the flotation circuit in which the copper is substantially recovered in the final concentrate and the gangue discarded. It the hydrogen ion content of the solution is sumclently high in the reject as taken from the cleaner so that the oxide copper is converted to metallic by agitation with metallic iron then no addition of acid will be required. Also, in case of only slight oxide coatings the abrasive action occurring in the agitation treatment oi the reject may give adequate conditioning oi the solid particles. In case of sufliclent capacity of the main metallic iron precipitating apparatus, aswell as oi the rougher flotation, my method is most simply conducted by adding the rejects in to the feed of the metallic iron precipitating apparatus from whence it returns with the normal pulp advance to the head of the rougher flotation cell. The leached pulp entering the precipitators from the leaching agitators contains normally sumcient free acid to eiiect the dissolution of the oxide copper in the reject but not the cement copper. However, in certain cases this reject pulp may be given a separate acidiflcaflm. Bellini-ion, contact with metallic iron and flotation according to local conditions and requirements. In such cases these secondary flotation products resulting may beend productsinthesystemorthey maybe added to other flotation stages.

Without departing from the purpose of this invention some other precipitant, such as a sulphide, may supplement or replace the metallic iron in re-conditioning these rejects. In such case the dissolved copper is precipitated as a sulphide and the oxidized surfaces 0! the solid particles are filmed with sulphide, both types of particles then being amenable to the subsequent flotation treatment.

Summarizing this method, it has been found that re-circulation and aeration of cement copper products lower the floatability due to oxidation of cement copper, resulting in increased tailing losses. Such losses may be minimised by changing the chemical nature of the oxidised copper thus formed in the normally re-circulating products so that floatable forms are produced, the product then being given a subsequent flota tion treatment for recovery of the copper and discarding of the gangue. Also, by such treatment dissolved and dimcultly floatable forms of copper present in the original cement copper flotation feed andoccurring in the recirculating products are also made readily floatahle, and are thus recovered as a high grade final concentrate with the other copper present. Thus, this method may operate as an improvement on and in conjunction with the means for inhibiting re-solution of cement copper as described in the above patent and which causes to be produced certain oxidised iorms oi copper which are found in the so-called middling products.

I claim:-

1. In a method of recovering cmnent copper from an ore pulp by a leaching-precipitation-flotatlon process the steps of separating from the flotation system products intermediate the con centrate and tailing as to grade, the said products having had their floatability impaired by oxidation subsequent to the precipitation step, producing metallic copper surfaces upon said products, and recovering the metallic copper particles from the pulp by flotation.

2. In a method of recovering cement copper from an ore pulp by a leaching-precipitationflotation process the steps 0! separating from the flotation system products intermediate the concentrate and tailing as to grade, the said products containing dissolved copper and copper oxidized subsequent to the precipitation ch8 dissolving the oxidized copper, precipitating the dissolved copper, and recovering the copper values from the pulp by flotation.

3. A process of recovering cement copper from an ore pulp comprising treating said pulp by flotation to produce a final concentrate. a flnal tailing, and a product intermediate the grade of said concentrate and tailing and which contains cement copper oxidized by the action oi air in the above treatment, separating said intermediate product, subjecting said intermediate product to a preferential chemical treatment whereby said oxidized copper is dissolved and back Patent No. 2,070,133

toafloatahletonn'iflimdimoivinganycontainedmeiallicco muzandthenrecoveringthecoppernhmmtheproductbya flotafiont.

LAzmethodoifcementcopperfrom an ore pulp by a leaching-precipitation-flotaflon process, comprising inhibiting re-soiutlon oi the cement copper otter the precipitation step, produdngintheiiotaflmstageaflnaiconeentrate. aiinaltailing,andaproductintermediate the grade of said concentrate and tailing, separating the saidinteunediate product-from the flotation system,addinganacidtotbeintermediateprodmttodissolvesubstanflalbonlytheoxideeoppenagitatingwithmltaeraflontheaddifledpulp, contactingmidpulpwith metallic iron totherebypreeimtatemetallic irom the solution. and subjeclim said pulp treatmenttorecoverfliemetaliieeoppervame.

5.Amethodofcunentcopperfrom anoreieachingamlipotanoxidized copperore,preeipitating metallichmmbiectinstheprecipitatedpiflpto a flotation treatment to produce aflnal concentrate, a final tailing and apmduct intermediate thegradeotsaidconomhateandtailinmseparatinasaidintermediate mdimtnmntheflotation system, and reintroducing the product to the aboveatmmepoint ahead of new emu MN m BAR-KORE.

Granted February 9, 1937 HABHON E. KEYES The above entitled patent was extended October 2, 1951, under the provisions of the Act of June 30, 1950, for 6 years and 82 days from the expiration of the original term thereof.

Goa-drainer of Patents.

to flotation I claim:-

1. In a method of recovering cmnent copper from an ore pulp by a leaching-precipitation-flotatlon process the steps of separating from the flotation system products intermediate the con centrate and tailing as to grade, the said products having had their floatability impaired by oxidation subsequent to the precipitation step, producing metallic copper surfaces upon said products, and recovering the metallic copper particles from the pulp by flotation.

2. In a method of recovering cement copper from an ore pulp by a leaching-precipitationflotation process the steps 0! separating from the flotation system products intermediate the concentrate and tailing as to grade, the said products containing dissolved copper and copper oxidized subsequent to the precipitation ch8 dissolving the oxidized copper, precipitating the dissolved copper, and recovering the copper values from the pulp by flotation.

3. A process of recovering cement copper from an ore pulp comprising treating said pulp by flotation to produce a final concentrate. a flnal tailing, and a product intermediate the grade of said concentrate and tailing and which contains cement copper oxidized by the action oi air in the above treatment, separating said intermediate product, subjecting said intermediate product to a preferential chemical treatment whereby said oxidized copper is dissolved and back Patent No. 2,070,133

toafloatahletonn'iflimdimoivinganycontainedmeiallicco muzandthenrecoveringthecoppernhmmtheproductbya flotafiont.

LAzmethodoifcementcopperfrom an ore pulp by a leaching-precipitation-flotaflon process, comprising inhibiting re-soiutlon oi the cement copper otter the precipitation step, produdngintheiiotaflmstageaflnaiconeentrate. aiinaltailing,andaproductintermediate the grade of said concentrate and tailing, separating the saidinteunediate product-from the flotation system,addinganacidtotbeintermediateprodmttodissolvesubstanflalbonlytheoxideeoppenagitatingwithmltaeraflontheaddifledpulp, contactingmidpulpwith metallic iron totherebypreeimtatemetallic irom the solution. and subjeclim said pulp treatmenttorecoverfliemetaliieeoppervame.

5.Amethodofcunentcopperfrom anoreieachingamlipotanoxidized copperore,preeipitating metallichmmbiectinstheprecipitatedpiflpto a flotation treatment to produce aflnal concentrate, a final tailing and apmduct intermediate thegradeotsaidconomhateandtailinmseparatinasaidintermediate mdimtnmntheflotation system, and reintroducing the product to the aboveatmmepoint ahead of new emu MN m BAR-KORE.

Granted February 9, 1937 HABHON E. KEYES The above entitled patent was extended October 2, 1951, under the provisions of the Act of June 30, 1950, for 6 years and 82 days from the expiration of the original term thereof.

Goa-drainer of Patents.

to flotation Patent No. 2,070,133 Gnnhed February 9, 1937 HARMON E. KEYES The above entitled patent was extended October 2, 1951, under the provisions of the Act of June 30, 1950, for 6 yeam end 82 (hys from the expiration of the original term thereof.

C'ouwu'uiour of Patents. 

